On screen he has played a convict and a hustler, both of whom end up in the money. Off‑screen last week, Eddie Murphy, the 22‑year-old "Saturday Night Live" star, came out a winner once again. On the heels of his dazzling performances in "48 Hours" and "Trading Places," Paramount Pictures signed Murphy to a $15 million, five‑film deal. According to Murphy's manager, the studio's con­tract with the comic "puts us in a situation where there is no way he can lose." That sentiment was echoed in New York City's Washington Square Park by one of Murphy's comedic colleagues, Charlie Barnett, 28. "He was born with a silver spoon in his mouth," says Barnett, inflating Murphy's middle‑class background. Their rivalry dates back to 1979 when Barnett auditioned for a role in "SNL" but couldn't make sense of the cue cards because he couldn't read. The job eventually went to Murphy, although Barnett says decisively, "I'm funnier." Come April, Barnett's boast will be put to the test when he makes his screen debut alongside Mr. Tin "D.C. Cab," a comedy about taxi drivers set in Washington.